Referring to FIG. 5, an electronic control device includes a housing and an electronic circuit board 510. The control device is used for an internal combustion engine for a vehicle. The housing is constructed of a case 520 and a cover 530, and houses the electronic circuit board 510. The circuit board 510 is fixed to an inner wall of the cover 530 adjacent to connectors 540, and electrically connected to the connectors 540 via bonding wires 550. With this configuration, an area of the control device mounted on an engine is relatively small.
In such an electronic control device, heat-producing component 511, such as a semiconductor switch, may be mounted on the circuit board 510. Heat produced in the heat-producing components is transmitted to the inside surface of the cover 530, and the outside surface. Then, the heat is released to an inner space of an engine compartment. The heat is also transmitted from an inner wall of the cover 530 to an engine block via a side wall 530h. 
However, improving heat dissipation is not fully considered in the control device. The temperature of the engine compartment is close to the highest heat-resistant temperature of the component 511. Therefore, releasing the heat via heat radiation is limited. On the other hand, an engine block is generally cooler than a room temperature of an engine compartment. Therefore, releasing the heat via the engine block is effective. However, the side wall 530h of the cover 530 is relatively thin and thermal resistance is high. Thus, an efficiency of the heat conduction is low.
To solve this problem, another electronic control device shown in FIG. 6A is provided. A circuit board 610 is directly mounted on the base 620 to reduce the thermal resistance, as shown in FIG. 6A. To connect the connectors 640 to the circuit board 610 via bonding wires 650, bonding terminals 640a need to be extended from the connectors 640 along the circuit board 610. Therefore, the size of the control device becomes large.
Referring to FIG. 6B, bonding terminals 610a and bonding terminals 640a are provided on the circuit board 610a and on the outer periphery of the connectors 640, respectively. The bonding terminals 610a and the bonding terminals 640a are substantially perpendicular to each other and connected together via bonding wires 650. However, a bonding device for bonding the terminals 610a, 640a with the bonding wires 650 is not commonly used. Developing of the device may affect a manufacturing cost of the control device.
Furthermore, making an engine compartment small in size and high in density is a social demand from the point of view of resource-savings. To meet the demand, the electronic control device needs to be improved in heat-dissipation efficiency and to be small in size. Even though the control device is used under the high temperature, the control device is still expected to have high heat-dissipation efficiency and to be small in size.